I think for drama he might believe Seerat plus Brar's haven't been very logic friendly so far... maybe by then they will be.
But I don't think Angad would force himself on Sahiba as he is a modified Riddhi. I think he is going to be drunk and confess his love for Seerat and pass out. Plus here they made a point in the show as well as in the promos to show that Angad only likes Seerat as he believes her to have the qualities that Sahiba has... so he is actually in love with Sahiba. He is a typical itv male that kind hearted and sensitive behind the rich and egotistical dudes facade (Asad Ahmed Khan, Shivaay Singh Oberoi, Ahaan Veer Malhotra type... you know all the recent ITV males). So I am pretty sure they would modify the story from the original.
P.S. writing this made me think how even the parallel male leads have a trope... the fun loving and fan favorite who root for their bhai-bhabhi and solve their issues, and are sorted in life (as compared to the male lead) like Ayaan was for Asad, Rudra for Shivaay, and Kartik for Ahaan and here they have Veer for Angad